Intake air control device and internal combustion engine mounting the same

ABSTRACT

A main passage mounting a throttle valve and an air bypass flow passage for reducing HC emission by promoting atomization of the fuel spray injected from the assembly pipe fuel injector are integrated in a body of an intake air control device arranged upstream of an assembly pipe in one-piece structure to form a unit. Thereby, the intake air control device can be easily manufactured, and easily mounted on and dismounted from the intake air system. An amount of HC emitted at warming-up operation of an internal combustion engine is reduced by efficiently supplying fuel spray injected from an assembly pipe fuel injector at starting and warming-up operations to the internal combustion engine.

BACKGROUND OF THE INVENTION

[0001] 1. Technical Field

[0002] The present invention relates to an intake air control device and an internal combustion engine mounting an intake air control device, and particularly to a technology improving combustion performance of an internal combustion engine and reducing an amount of hydrocarbon (hereinafter, referred to as HC) emitted at warming-up operation of the internal combustion engine.

[0003] 2. Prior Art

[0004] An intake air control device for an engine is disclosed in Japanese Patent Application Laid-Open Hei 4-232353. In the intake air control device, a cold-start injector projecting inside a main intake air passage is arranged at a position near an outer peripheral portion of a throttle valve when the throttle valve is in a partially open position.

[0005] However, it is difficult that a fuel spray injected in the main intake air passage from the cold-start injector projecting inside the main intake air passage is sufficiently vaporized (atomized) and transported to each of combustion chambers by an intake air flowing the main intake air passage, and most of the fuel spray is adhered onto the inner surface of the main intake air passage to be stagnated. Therefore, it is difficult to stably supply the sufficiently a vaporized fuel to each of the combustion chambers.

[0006] Further, a cold-start fuel control system comprising a cold-start fuel injector, a heater and an idle speed control valve (hereinafter, referred to as ISC valve) is disclosed in the specification and drawings of U.S. Pat. No. 5,482,023.

[0007] In this system, a part of the air from the ISC valve (a first air flow) is merged with fuel injected from the cold-start fuel injector. Therefore, an opening of an air flow passage from the ISC valve is arranged in an annular shape so as to surrounding an outlet portion of the cold-start fuel injector. The fuel from the cold-start fuel injector with the first air flow just after merging enters into an inside of a cylindrical heater arranged in a row downstream of the cold-start fuel injector.

[0008] On the other hand, an air passage for allowing part of the air from the ISC valve to flow therethrough is formed in the outside periphery of the heater, and the air flowing through this air passage (a second air flow) merges with the fuel spray passed through the inside of the heater at the outlet portion of the heater. The fuel coming out from the cold-start fuel injector is promoted to be vaporized while passing through the inside of the heater, and is further promoted to be vaporized by being mixed with the second air flow at the outlet portion of the heater. The outlet portion of the heater is communicated with the intake assembly pipe, and the fuel spray promoted in vaporization is distributed to each of the cylinders after being discharged into the intake assembly pipe.

[0009] In the system, a mixing chamber for mixing the fuel and the air inside the cylindrical heater is formed to form a kind of atomizer having a heater exit as the outlet by arranging from the upstream side in order of the cold-start fuel injector, the merging point of the fuel injected from the cold-start fuel injector with the air flow and the mixing chamber constructed inside the heater in a row. It can be considered that the atomizer is an air assist type atomizer which uses energy of the air flow, and is also an internal mixing type atomizer which performs air-liquid mixing by merging the fuel with the air inside the atomizer.

[0010] In the system, the second air flow flows into the outer peripheral portion of the heater, and merged with the fuel spray passed through the inside of the heater while flowing in the same direction to promote vaporization of the fuel spray. However, in the system, the merging of the fuel spray to the intake pipe and the transportation in the intake pipe after that is not sufficiently taken into consideration.

[0011] In the system, the fuel injected from the cold-start fuel injector is promoted in vaporization by passing through the narrow and long passage formed inside the heater while contacting with the heater. However, in the system, the vaporizing efficiency by the heater is not sufficiently taken into consideration.

[0012] In the system, the outlet portion of the heater is communicated with the intake assembly pipe, and the fuel spray promoted in vaporization is discharged into the intake assembly pipe, and then distributed to each of the cylinders. However, in the system, improvement of the distribution to each of the cylinders is not sufficiently taken into consideration.

SUMMARY OF THE INVENTION

[0013] An object of the present invention is to provide an intake air control device preferable for reducing an amount of HC emitted at warming-up operation of an internal combustion engine.

[0014] Another object of the present invention is to construct an intake air control device which is easily manufactured, and easily mounted and dismounted.

[0015] A further object of the present invention is to reduce an amount of fuel adhering onto a wall surface of the intake pipe and to reduce an amount of HC emitted at warming-up operation of an internal combustion engine by improving the merging of the fuel injected from a second injector to the intake pipe and the transportation of the fuel to the downstream side, the second fuel injector being additionally arranged separately from a first fuel injector arranged at a position near the cylinder of an internal combustion engine and used at starting operation of the internal combustion engine.

[0016] A still further object of the present invention is to decrease electric energy consumed by a heater for atomizing the fuel spray by modifying behavior of contact of the fuel spray with the heater.

[0017] A further object of the present invention is to improve uniformity in distribution of the fuel spray to each of the cylinders by modifying the method of supplying the fuel spray to the intake pipe.

[0018] The present invention is characterized by an intake air control device comprising a body having a main flow passage for supplying air to cylinders of an internal combustion engine and a throttle valve for controlling an air flow rate arranged inside the main flow passage; and a fuel injector for supplying fuel into the main flow passage, the fuel injector being fit and attached to the body, wherein the body is formed by working a body member into a one-piece structure comprising an opening portion communicating an outer portion of the body with the main flow passage is a downstream side of the throttle valve; a mounting portion for fitting and attaching the fuel injector facing an opening plane of the opening portion; a first bypass flow passage communicating with the inside of the main flow passage through the opening portion, the first bypass flow passage being branched from the main flow passage in the upstream side of the throttle valve; and a second bypass flow passage communicating with the inside of the main flow passage in the downstream side of the throttle valve and in the upstream side or the downstream side of the opening portion, the second bypass flow passage being branched from the main flow passage in the upstream side of the throttle valve.

BRIEF DESCRIPTION OF DRAWINGS

[0019]FIG. 1 is a diagram showing the system structure of the first embodiment of an intake air control device in accordance with the present invention and an internal combustion engine mounting the intake air control device;

[0020]FIG. 2 is an enlarged view showing the first embodiment of the intake air control device in accordance with the present invention,

[0021]FIG. 2(a) is a vertical cross-sectional side view,

[0022]FIG. 2(b) is a cross-sectional view being taking on the plane of the line A-A of FIG. 2(a), and

[0023]FIG. 2(c) is an enlarged view showing the front end portion of the fuel injector;

[0024]FIG. 3 is a cross-sectional view being taking on the plane of the line B-B of FIG. 3(a), and a cross-sectional view being taking on the plane of the line C-C of FIG. 3(a);

[0025]FIG. 4 is graphs showing atomization characteristics of the fuel spray,

[0026]FIG. 4(a) is a graph showing the relationship between average droplet size and gas-to-liquid volumetric flow rate ratio which is the volumetric flow rate ratio of air collide with the fuel spray to the fuel spray injected from the fuel injector, and

[0027]FIG. 4(b) is a graph showing the distribution of droplet size;

[0028]FIG. 5 is graphs showing characteristics of electric power supplied to a heater,

[0029]FIG. 5(a) is a graph showing the relationship between voltage applied to the heater and time, and

[0030]FIG. 5(b) is a graph showing the relationship between current flowing in the heater and time;

[0031]FIG. 6 is graphs showing the operating conditions and the exhaust characteristics,

[0032]FIG. 6(a) is a graph showing the relationship between average droplet size and ignition timing,

[0033]FIG. 6(b) is a graph showing the relationship between ignition timing and temperature of catalyst, and

[0034]FIG. 6(c) is a graph showing the relationship between rising time of catalyst temperature of FIG. 6(b) and amount of exhausted HC;

[0035]FIG. 7 is charts showing the relationship between injection timing of each fuel injector and time,

[0036]FIG. 7(a) is charts showing timing of operation of switching an assembly pipe fuel injector and a port fuel injector,

[0037]FIG. 7(b) and FIG. 7(c) are charts showing a control signal of an opening-and-closing valve under operation of the assembly pipe fuel injector;

[0038]FIG. 8 is a view showing the second embodiment of an intake air control device in accordance with the present invention,

[0039]FIG. 8(a) is a vertical cross-sectional side view, and

[0040]FIG. 8(b) is a cross-sectional view being taking on the plane of the line A-A of FIG. 8(a);

[0041]FIG. 9 is a view showing the third embodiment of the intake air control device in accordance with the present invention,

[0042]FIG. 9(a) is a vertical cross-sectional side view,

[0043]FIG. 9(b) is a cross-sectional view being taking on the plane of the line A-A of FIG. 9(a), and

[0044]FIG. 9(c) is a cross-sectional view being taking on the plane of the line C-C of FIG. 9(a);

[0045]FIG. 10 is a view showing the fourth embodiment of an intake air control device in accordance with the present invention,

[0046]FIG. 10(a) is a vertical cross-sectional side view, and

[0047]FIG. 10(b) is a cross-sectional view seeing in the direction shown by the arrow A of FIG. 10(a);

[0048]FIG. 11 is a view showing the fifth embodiment of an intake air control device in accordance with the present invention,

[0049]FIG. 11(a) is a vertical cross-sectional side view, and

[0050]FIG. 11(b) is a cross-sectional view being taking on the plane of the line C-C of FIG. 11(a).

[0051]FIG. 12 is a view showing the sixth embodiment of an intake air control device in accordance with the present invention;

[0052]FIG. 13 is a view showing the seventh embodiment of an intake air control device in accordance with the present invention,

[0053]FIG. 13(a) is a vertical cross-sectional side view, and

[0054]FIG. 13(b) is a cross-sectional view being taking on the plane of the line A-A of FIG. 13(a).

[0055]FIG. 14 is a view showing the eighth embodiment of an intake air control device in accordance with the present invention;

[0056]FIG. 15 is a view showing the ninth embodiment of an intake air control device in accordance with the present invention;

[0057]FIG. 16 is a view showing the tenth embodiment of an intake air control device in accordance with the present invention;

[0058]FIG. 17 is a view showing the eleventh embodiment of an intake air control device in accordance with the present invention;

[0059]FIG. 18 is a view showing the twelfth embodiment of an intake air control device in accordance with the present invention,

[0060]FIG. 18(a) is a vertical cross-sectional side view, and

[0061]FIG. 18(b) is a cross-sectional view being taking on the plane of the line A-A of FIG. 18(a); and

[0062]FIG. 19 is a diagram explaining spray shapes depending on difference in the shape of spray hole in a front end of various kinds of fuel injectors which are to be applied to the intake air control device in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION

[0063] The first embodiment of an intake air control device and an internal combustion engine mounting an intake air control device in accordance with the present invention will be described below, referring to FIG. 1 to FIG. 7.

[0064] Referring to FIG. 1, an internal combustion engine 1 is a well-known multi-cylinder internal engine of a spark ignition type using gasoline as the fuel, but only one of the cylinders is illustrated in the figure.

[0065] The intake air system, is composed of an air flow sensor 3 for measuring a flow rate of intake air 100 sucked through an air cleaner (not shown); an intake air control device 110 containing a throttle valve 4 of which opening-and-closing operation is linked to accelerator operation of a driver; a throttle valve positioning sensor 5 for measuring an opening degree of the throttle valve 4; an intake air assembly pipe 6; an intake air manifold 7 for branching the intake air assembly pipe 6 to each of the cylinders; and an intake air port 8 having an intake air valve 31. The intake air assembly pipe means an intake air pipe before branching to each of the cylinders. An amount of intake air and an opening degree of the throttle valve 4 measured by the air flow sensor 3 and the throttle valve positioning sensor 5 are input to a controller 32 to be used for detecting of operating conditions and various kinds of a control of the internal combustion engine 1.

[0066] The exhaust gas system is composed of an exhaust port 21 having an exhaust valve 34 of each of the cylinders; an exhaust manifold 22; an oxygen concentration sensor 23 for measuring an oxygen concentration in the exhaust gas; a ternary catalyst converter 24 for purifying the exhaust gas; and a silencer muffler (not shown in figure). Further, the oxygen concentration measured by the oxygen concentration sensor 23 is input to the controller 32 to be used for detecting of operating conditions and various kinds of the control of the internal combustion engine 1.

[0067] The fuel system is composed of a fuel tank 26 for storing fuel 2; a fuel pump 27 for pressurizing and pumping the fuel 2 from the fuel tank 26; a fuel filter 28; a pressure regulator 29 for regulating pressure of the pumped fuel 2 to an appropriate pressure; port fuel injectors 10 of first fuel injectors for injecting fuel to the intake air ports 8 of the cylinders (#1, #2, . . . ), respectively; and an assembly pipe fuel injector 15 of a component of the second fuel injector for injecting fuel to be supplied to the intake assembly pipe 6, and these components are connected by fuel piping 30. The assembly pipe fuel injector 15 is a fuel injector arranged downstream of the throttle valve 4 of the main flow passage 12 and upstream of the intake air assembly pipe 6, and accordingly called as the assembly pipe fuel injector in order to discriminate from the port fuel injector 10.

[0068] An injection of the fuel 2 from the assembly pipe fuel injector 15 and the port fuel injector 10 is controlled corresponding to an operating condition of the internal combustion engine 1, in detail, performed based on a command signal output from the controller 32. The fuel injection of the assembly pipe fuel injector 15 and the port fuel injector 10 is switched corresponding to starting of operation of the internal engine 1, an operation during a preset period after starting and an operating condition of the internal combustion engine 1 after then, but the detail is to be described later.

[0069] The intake air control device 110 is formed in a unit easily mounting on and dismounting from the intake air system of the internal combustion engine 1 by integrating the second fuel injector having the assembly pipe fuel injector in a one-piece structure so as to be contained inside the single body 11. The structure and the operation are to be described later.

[0070] Each of the cylinders of the internal combustion engine 1 comprises a combustion chamber 25 in which an ignition plug 33 is arranged so as to exposed to the combustion chamber 25; and an intake valve 31 and an exhaust valve 34 for controlling the cycle of intake stroke, compression stroke, expansion stroke and exhaust stroke by opening and closing operation. Electric power supplied from a battery and an alternator (both are not shown in the figure) is converted to high voltage electric power by an ignition coil 40, and the high voltage electric power is distributed to the ignition plugs 33 to perform spark ignition at appropriate timings corresponding to signals from the controller 32.

[0071] A water jacket 36 is provided in the side portion of the combustion chamber 25 the inside of which cooling water 35 for cooling the internal combustion engine 1 is circulated. Temperature of the cooling water 35 is measured by a water temperature sensor 37 arranged in the water jacket 36, and input to the controller 32 to be used for detecting the operating condition of the internal combustion engine 1 and controlling the internal combustion engine 1.

[0072] Further, a rotation angle of a crank shaft (not shown in the figure) linked to a piston 38 through a connection rod 39 is measured by a crank angle sensor (not shown in the figure). The controller 32 can be detected a position of the piston 38 by inputting the measured value from the crank angle sensor to the controlled 32.

[0073] As the internal combustion engine 1 is operated, mixed gas of the fuel injected from the assembly pipe fuel injector 15 or the port fuel injector 10 and the intake air 100 is sucked into the combustion chamber 25, the mixed gas sucked into the combustion chamber 25 is ignited by the ignition plug 33 at time near the top dead point between compression stroke and expansion stroke to be burned. The burned gas 107 after combustion is discharged from the combustion chamber 25, and then flows to the ternary catalyst converter 24 through the exhaust port 21 and the exhaust manifold 22 to be purified there, and is exhausted to the outside of the internal combustion engine 1 as a final exhaust gas 106.

[0074] The construction of the intake air control device 110 will be described below, referring to FIG. 2.

[0075] The intake air control device 110 comprises the main passage 12 formed in a body 11 having joining flanges to the intake air system in the both ends; and the throttle valve 4 arranged inside the main passage 12. By opening the throttle valve 4, the upstream side and the downstream side are communicated with each other. Further, in the body 11 forming the main passage 12 of the intake air control device 110, the bypass flow passage 13 connecting (communicating) between the upstream side and the downstream side of the throttle valve 4 is formed separately from the main passage 12. An ISC valve 14 is arranged in the bypass flow passage 13, and a flow rate of air 101 flowing through the bypass flow passage 13 is controlled by opening and closing the ISC valve 14 at starting operation of the internal combustion engine 1 and during idling operation in warming-up operation of the internal combustion engine 1.

[0076] The bypass flow passage 13 is branched to flow passages 13 a, 13 b in the downstream side of the ISC valve 14. One of the bypass flow passage 13 a communicates with a fuel injector inserting portion 16 formed as a circular depressed portion so as to communicate with the main passage 12 from the outside of the body 11. The fuel injector inserting portion 16 is an attaching portion for attaching the assembly pipe fuel injector 15, and formed in slanting by an angle α to the axial flow direction of the main passage 12 in the body 11, and the depth end (the bottom portion) of the fuel injector inserting portion 16 is opened to the circular depressed portion 161 formed in the main passage 12 side in the body 11, and the outer end is opened to the outside of the body 11. The assembly pipe fuel injector 15 is inserted into the fuel injector inserting portion 16 to be attached to the body 11 of the intake air control device 110 and to be sealed with a seal ring 151. By doing so, a pressure regulation chamber 41 is formed around the assembly pipe fuel injector 15. The bypass flow passage 13 a is communicated with the pressure regulation chamber 41.

[0077] An angle between a center line of the fuel spray assumed to be a spray direction of the assembly pipe fuel injector 15 and a center axis line passing through the center of the main passage 12 and assumed to be the axial flow direction is set to the angle α.

[0078] In order to easily form the body 11 of the intake air control device 110, the assembly pipe fuel injector 15 may be formed so as to be attached the body 11 through an adapter though there is a possibility of increasing in the device size and in man-hours of assembling the device.

[0079] The center line of the fuel spray is considered to be a center line connecting between the center of the fuel injection hole of the fuel injector and the central point of a cross section of the injected fuel spray. In general, the center line of the fuel spray agrees with a driven direction of the valve body of the fuel injector, or agrees with an axis of the valve shaft set to a direction of driving shaft for driving the valve body, or agrees with a center line of the fuel injection hole passing through the center of the fuel injection hole and parallel to the wall surface forming the injection hole. However, when the fuel injection hole is slanted to the valve axis or the outlet of the fuel injection hole is modified, the center line of the fuel spray does not always agree with the valve axis or the center line of the fuel injection hole.

[0080] In the bottom portion of the pressure regulation chamber 41 arranged in the depressed portion 161 of the main passage 12, a nozzle 47 of the assembly pipe fuel injector 15 is placed, and a circular hole 46 opening to just below the injection hole portion of the nozzle 47 is formed to communicate with the main passage 12 downstream of the throttle valve 4 through the depressed portion 161. The side portion of the nozzle 47 of the assembly pipe fuel injector 15 is positioned by being guided by a guide surface 48 formed in the inner peripheral portion of a plurality of passage forming projected portions provided in the bottom portion of the pressure regulation chamber 41. Further, the outlet end portion of the nozzle 47 is placed with a very small gap in the inner surface of the circular hole 46 in the inner side of the guide surface 48, and the passage forming projected portions 49 set the height of the gap. The end surface 50 of the passage forming projected portions 49 is brought in contact with the shoulder portion 15 of the assembly pipe fuel injector 15, and the contact surface is illustrated by the dotted line in the FIG. 2(b). The portions between the plurality of passage forming projected portions 49 make the pressure regulation chamber 41 communicate with the circular hole 47. Therein, the circular hole 46 is formed in a shape having as a thin thickness in the axial direction as possible, that is, what is called as a thin edge orifice.

[0081] On the other hand, the other bypass flow passage 13 b branched from a branch inlet portion 43 provided in the downstream portion of the ISC valve 14 is communicated with a pressure regulation chamber 42 through a branch outlet portion 44. The pressure regulation chamber 42 is communicated with the main passage 12 by a plurality of carrier air passage 45 formed opposite to each other so as to be directed toward the center axis line in the axial flow direction of the main passage 12. In the present embodiment, the carrier air passage 45 is formed in the downstream side of a heater 18 to be described below.

[0082] The heater 18 of a heating body for generating heat to evaporate fuel is formed by arranging a plurality of plate-shaped heater elements in an arc-shape along the inner wall surface of the main passage 12, and the heater element is a PTC heater (a ceramic heater) which has a function of keeping its temperature constant by reducing current by rapidly increasing the electric resistance when the temperature rises above a preset value. A thermal insulator 19 for reducing heat transfer from the heater 18 to the wall surface of the main passage 12 is arranged between the heater 18 and the main passage 12.

[0083] Further, a projected portion 20 is provided on the wall surface of the main passage in the upstream portion of the heater 18 so as to preventing the air flowing from the upstream side of the heater 18 from directly hitting onto the heater 18, but the projected portion 20 may be eliminated when an amount of the air flowing from the upstream side and hitting onto the heater is small.

[0084] The structure of flow passage from the bypass flow passage 13 b to the main passage 12 through the branch outlet portion 44, the pressure regulation chamber 42 and the carrier air passage 45 will be described below, referring to FIG. 3(a) and FIG. 3(b). FIG. 3(a) and FIG. 3(b) are a cross-sectional view being taken on the plane BB in FIG. 2(a) and a cross-sectional view being taken on the plane C-C, respectively.

[0085] The pressure regulation chamber 42 is an annular space arranged in the outer peripheral side of the main passage 12, and communicated with the main passage 12 through the carrier air passage 45. The carrier air passage 45 communicates between the pressure regulation chamber 42. Four of the carrier air passages 45 are formed so as to open to the inner peripheral wall of the main passage 12 downstream of the heater 18 in the main passage 12, and are arranged so as to be opposite to each other.

[0086] According to the present embodiment, the intake air control device 110 is constructed by forming the injector inserting portion 16 of the assembly pipe fuel injector 15, the bypass flow passages 13, 13 a and 13 b, the depressed portion 161, the pressure regulation chambers 41 and 42, the atomizing air passage (the passage from the pressure regulation chamber 41 to the circular hole 46 through which the air 103 flows) and the carrier air passage 45 in the body forming the main passage 12 in the one-piece structure, and by mounting the throttle valve 4, the drive mechanism of the throttle valve 4 (not shown in the figure), the assembly pipe fuel injector 15, the ISC valve 14 and the heater 18. Therefore, the intake air control device 110 is formed detachable to the intake pipe as a unit. Since the important device relating to starting and warming-up operation of the internal combustion engine 1 can be mounted onto and dismounted from the internal combustion engine 1 as a unit, the assembling, the adjustment and the maintenance can be easily performed.

[0087] If the body 11 is formed through resin molding, the body 11 of such a kind can be efficiently manufactured, and the intake air control device 110 can be made light in weight. The resin molded body can be employed in the embodiments to be described later.

[0088] Effects of the air flowing in the bypass flow passages 13 a, 13 b will be described below. The air flowing in the bypass flow passage 13 a flows from the periphery of the nozzle 47 of the assembly pipe fuel injector 15 into the annular gap formed between the outlet end portion of the nozzle 47 and the circular hole 46, and collides (merges) with the fuel injected from the assembly pipe fuel injector 15 from a direction crossing the injection direction of the fuel. Then, the air flows out through the circular hole 46 formed below the axis of the assembly pipe fuel injector 15 into the depressed portion 161 opening to the main passage 12 to flow toward the heater 18 while dragging or inducing the fuel spray 17.

[0089] On the other hand, after flow is regulated in the pressure regulation chamber 42, the air 104 flowing the bypass flow passage 13 b flows from the plurality of carrier air passages 45 arranged opposite to each other into the main passage 12, and after colliding with each other, the flow directions are diverted toward the downstream side. The amount of the air 104 flowing in the bypass passage 13 b is most of the total air flow rate controlled by the ISC valve 14. That is, the air 104 flowing out from the carrier air flow passage 45 produces a strong drag flow in the downstream side of the heater 18, and drags the atomization-promoted fuel spray injected from the assembly pipe fuel injector 15 and the partially vaporized fuel vapor by the heater 18 to transport the downstream side.

[0090] Further, by setting the injection direction of the fuel spray 17 injected from the assembly pipe fuel injector 15 slanting by the angle α to the center axis line of the axial flow direction of the main passage 12, the fuel spray 17 is made easy to flow along the drag flow formed by the air 104 flowing out from the carrier air passage 45. Furthermore, since the carrier air passage 45 is arranged in the downstream side of the heater 18, the carrier air 104 does not directly remove the heat from the heater 18 when the carrier air flows in the main passage 12.

[0091] A ratio of air flow rates 103 and 104 flowing in the bypass flow passages 13 a, 13 b is determined by a ratio of an area of the air passage formed in the gap between the outlet end portion (a front end surface) of the nozzle 47 and the bottom surface of the injector inserting portion 16 having the circular hole 46 formed to the total area of the plurality of the carrier air passages 45. The present embodiment is designed so that the flow rate of the fuel atomizing air 103 may become sufficiently smaller compared to the flow rate of the carrier air 104.

[0092] Production of fuel spray 17 of the assembly pipe fuel injector 15 and effects of fuel vaporization will be described below.

[0093] In the present embodiment, the assembly pipe fuel injector 15 employs a fuel injector of an upstream swirl type which imparts swirl to the fuel inside the nozzle 47. That is, the fuel injector is the type that fuel spray in a thin-film 401 shape is sprayed by converting the pressure energy of the fuel to the swirl energy to promote the atomization. By assisting of the air 103 to the fuel spray 17 in the thin-film 401 shape, the atomization can be further rapidly promoted to produce a fine fuel spray 17. In addition, since the circular hole 46 is of a thin edge orifice shape, energy loss of the fuel and the air can be suppressed very small when the fuel and the air pass through the orifice (the circular hole 46), the atomization can be promoted.

[0094]FIG. 4(a) shows that the atomization is rapidly promoted by supplying the air 103. The portion P marked in the figure is the operating point used during the period (several tens seconds) after starting operation of the internal combustion engine 1 in the present embodiment, and the average droplet size of the fuel spray 7 is smaller than 10 μm. At that time, the amount of the air flow 103 flowing through the bypass flow passage 13 a is about {fraction (1/10)} of the total air flow controlled by the ISC valve 14. Therefore, the amount of the remaining intake air 104 can be effectively used for dragging and carrying the fuel spray 17.

[0095] Further, as shown in FIG. 4(b), number of the droplets of the fuel spray 17 having droplet size above 20 μm is only several percentage to the total number of the droplets. For example, the required time that a droplet of 20 μm becomes a suspendable droplet of 10 μm is 0.01 second under the conditions of fuel temperature of 20° C., and atmosphere of still air of 20° C. When the air velocity is 5 m/s, the traveling distance of the droplet until the droplet size becomes 10 μm is 5 cm. The construction of the present embodiment, number of droplets reach on the surface of the heater 18 can be substantially reduced. That is, when fuel spray 17 having droplet size distribution shown in FIG. 4(b) is supplied, most of the droplets are carried on the carrier air 104 to the downstream. Even if the droplets are attached onto the heater 18, they are instantaneously vaporized because of small droplet size.

[0096] As clear from the above description, according to the intake air control device of the present embodiment, the following characteristics can be obtained.

[0097] (1) As the assembly pipe fuel injector 15, the fuel injector of the upstream swirl type promoting atomization by adding swirl to the fuel in the inside of the nozzle is employed.

[0098] (2) By assisting (collision) of air to the fuel injected from the assembly pipe fuel injector 15, the atomization is further promoted.

[0099] (3) The amount of air 103 for atomization supplied to the assembly pipe fuel injector 15 is set to about 1/10 of the total amount of air required for operating the internal combustion engine 1 at warming-up operation.

[0100] (4) The remaining air 104 is used for carrying the fuel spray 17, and flows so as to not cool the heater 18.

[0101] (5) Most of the fuel spray 17 injected from the assembly pipe fuel injector 15 is carried by the air flow flowing in the intake air pipe.

[0102] (6) By constructing the second fuel injector including the bypass flow passages 13 a, 13 b in the body 11 of the intake air control device 110 containing the throttle valve 4 in a one-piece structure to form a unit, the device is made small in size.

[0103] (7) Since the fuel vaporizer having the heater 18 is constructed to be used as an auxiliary, the heater 18 may be eliminated when an amount of fuel reaching the heater 18 portion is little.

[0104] (8) The load of the heater 18 is substantially decreased, and accordingly the heater can be made small in size.

[0105] (9) Mounting ability of the intake air control device to the internal combustion engine is improved, and the productivity and the cost are largely improved compared to the conventional intake air control device.

[0106] Although in the present embodiment, the PTC heater is used for the heater 18, the ordinary heater such as an electric heat coil may be used if temperature control is performed by using a current control circuit. Further, although number of the carrier air passages 45 is set to 4, this purpose is to supply the air into the main passage 12 as uniformly as possible. Therefore, number of the carrier air passages 45 is not limited.

[0107] Operation of the fuel injector 110 when it is mounted on the internal combustion engine 1 will be described below, referring to FIG. 1 and FIG. 5 to FIG. 7.

[0108] Referring to the internal combustion engine 1 shown in FIG. 1, as the internal combustion engine 1 is operated, the intake pipe (the intake assembly pipe 6, the intake manifold 7, the intake port 8) downstream of the throttle valve 4 becomes a negative pressure. The air is sucked from the outside by the negative pressure. At starting operation and during idling operation, the throttle valve 4 is nearly in the fully closed condition, and the flow rate of the intake air in that state is controlled by the ISC valve 14 arranged in the bypass flow passage 13. The flow of the intake air in that time is schematically illustrated by the hollow arrows in the figure.

[0109] The air 100 sucked from the outside is filtered by the air cleaner (not shown in figure), and the flow rate is measured by the air flow sensor 3, and then the air reaches the upstream side of the throttle valve 4. A very small part of the intake air 100 flows into the main passage 12 in the downstream side of the throttle valve 4 through the small gap between the throttle valve 4 and the inner peripheral wall surface of the main passage 12 (the arrow 102). On the other hand, most of the intake air 100 flows from the upstream of the throttle valve 14 to the bypass flow passage 13 through the ISC valve 14 (the arrow 101), then the flow is split into two flows flowing out from the bypass flow passages 13 a , 13 b to the main passage 12.

[0110] Therein, at starting operation of the internal combustion engine 1 and during a predetermined period after starting, switching control between the assembly pipe fuel injector 15 and the port fuel injector 10 is performed. The control method will be described below, referring to FIG. 7.

[0111] At starting operation of the internal combustion engine 1, until the first explosion occurs in the combustion chamber 25, or until the rotation speed of the internal combustion engine 1 reaches a preset rotation speed, fuel is injected by operating the port fuel injector 10. After that, operation of fuel injection by the port fuel injector 10 is stopped to switch to operation of fuel injection operation by the assembly pipe fuel injector 15. At that time, fuel injection from the assembly pipe fuel injector 15 is performed by starting operation of the assembly pipe fuel injector 15 overlapping with the operating period of the port fuel injector 10 by a time period ΔT1. During the time period ΔT1, fuel is injected from both of the port fuel injector 10 and the assembly pipe fuel injector 15. The overlap time ΔT1 is a transport lag time until the fuel injected from the assembly pipe fuel injector reaches the combustion chamber 25.

[0112] By providing the overlap time ΔT1, it is possible to eliminate difference in torque generated by the internal combustion engine 1 caused at switching. The magnitude of the overlap time ΔT1 varies depending on the volume of the intake pipe downstream of the assembly pipe fuel injector 15 and the rotation speed of the internal combustion engine 1, and it is preferable that the value of the overlap time ΔT1 is increased as the volume is larger or as the rotation speed is slower. Particularly, the difference in the generated torque can be made further smaller by adding correction corresponding to the rotation speed, that is, the overlap time ΔT1 is set to a lager value when the rotation speed is low, and the overlap time ΔT1 is set to a smaller value when the rotation speed is high.

[0113] Further, by starting current supply to the heater in prior to fuel injection from the assembly pipe fuel injector 15, temperature of the heater at the time of starting fuel injection from the assembly pipe fuel injector 15 can be preheated up to a temperature required to vaporize the fuel. Therefore, vaporization of the fuel can be promoted.

[0114] Operation of fuel injection of the assembly pipe fuel injector 15 is continued for a predetermined period. For example, it is preferable that operation of fuel injection of the assembly pipe fuel injector 15 is continued during the warming-up period of the internal combustion engine 1, that is, until temperature of cooling water of the internal combustion engine 1 becomes the preset temperature. The purpose of fuel injection by the assembly pipe fuel injector 15 is to activate the ternary catalyst converter 24 in a short time by warming-up. In a case where a sensor for detecting temperature of the ternary catalyst converter 24 or a sensor for detecting temperature of exhaust gas passed through the ternary catalyst converter 24 is provided, it is preferable that operation of fuel injection of the assembly pipe fuel injector 15 is continued until temperature detected by the sensor rises up to a preset temperature.

[0115] After completion of the warming-up of the ternary catalyst converter 24, operation of fuel injection by the assembly pipe fuel injector 15 is stopped to switch operation of fuel injection by the port fuel injector 10. At that time, a time period ΔT2 that operation of fuel injection by both of the fuel injectors is stopped is provided between stopping of fuel injection by the assembly pipe fuel injector 15 and starting of fuel injection by the port fuel injector 10. By doing so, it is possible to eliminate difference in torque generated by the internal combustion engine 1 caused at switching. Similar to the overlap time ΔT1, the period time ΔT2 is also a transport lag time until the fuel injected from the assembly pipe fuel injector reaches the combustion chamber 25. Similarly to the overlap time ΔT1, it is preferable that the magnitude of the period time ΔT2 is controlled depending on the volume of the intake pipe downstream of the assembly pipe fuel injector 15 and the rotation speed of the internal combustion engine 1.

[0116] By performing the switching control of operation of fuel injection between the port fuel injector 10 and the assembly pipe fuel injector 15, the following effects can be obtained. That is, by injecting fuel from the port fuel injector 10 at starting operation of the internal combustion engine 1, the time required for starting operation can be shortened compared to the case where starting operation of the internal combustion engine 1 is performed by operation of fuel injection using only the assembly pipe fuel injector 15. This is because the fuel injected from the port fuel injector 10 can be soon sucked into and burned in the combustion chamber 25 of the internal combustion engine 1. Therefore, the starting operation time can be shortened by the time period corresponding to the transport lag time until the fuel injected from the assembly pipe fuel injector reaches the combustion chamber 25.

[0117] Description will be made below on a method of further promoting atomization of fuel by a method of supplying an opening-and-closing valve control signal during operation of fuel injection by the assembly pipe fuel injector 15, referring to FIG. 7(b) and FIG. 7(c).

[0118] In FIG. 7(b), an opening valve control signal of the assembly pipe fuel injector is repeated to be supplied with a given cycle of T. The given cycle here means, for example, a cycle in synchronism with the top dead point in intake stroke of each cylinder if the internal combustion engine 1. Since an amount of fuel injected from the assembly pipe fuel injector 15 is nearly in proportion to the time of supplying the opening valve control signal, a control signal having a long opening-valve time is supplied when the amount of injected fuel is increased, and a control signal having a short opening-valve time is supplied when the amount of injected fuel is decreased. That is, the amount of injected fuel is controlled by duty control of the control signal, and once of continuous fuel injection is performed during the given cycle T and the gas-liquid ratio during the fuel injection is constant.

[0119] On the other hand, in FIG. 7(c), plural times of fuel injection are intermittently performed during the cycle T though the amount of fuel injected from the assembly pipe fuel injector 15 during the cycle T is equal to the amount of FIG. 7(b). The gas-liquid ratio during fuel injection in this case becomes equal to that of FIG. 7(b). However, since the air from the circular hole 46 is continued to flow during closing-valve after the short injection, the ratio of air supplied to the fuel becomes larger compared to that in the case of FIG. 7(b) when a cycle T′ is taken into consideration. That is, the amount of air mixed with the fuel can be increased by doing the intermittent injection, and as the result, the atomization of the fuel by air can be further promoted, and the carrying power of fuel by air can be increased. Therein, seeing the signal supplied to the assembly pipe fuel injector 15, a short cycle ON-OFF signal compared to a cycle of ON-OFF of the control signal supplied to the port fuel injector 10 can be observed when the rotation speed of the internal combustion engine 1 is the same.

[0120] As shown in FIG. 5(a), a constant voltage is applied to the heater 18 from the battery and the generator such as the alternator or the like. Current flowing in the heater 18 varies with time, as shown in FIG. 5(b). That is, since the PCT heater is used as the heater 18 in the present embodiment, when temperature of the heater 18 is low at just after starting current supply, the resistance value of the heater 18 is small and a large current flows in the heater 18. Since the resistance of the heater 18 is acceleratively increased as the temperature of the heater 18 is raised, the current is decreased after reaching its peak, and finally settled to a current value of generating an amount of heat balancing to an amount of heat removed from the heater 18. The solid line in FIG. 5(b) indicates the time variation of current flowing in the heater 18 obtained by the effect obtained by the present embodiment. The characteristic will be described below, comparing to that of the conventional device shown by the dotted line in the figure.

[0121] (1) Since the heater is made small in size to reduce the heat capacity of the heater itself, the peak current can be reduced. Further, the current can reach the peak current in a short time (that is, the heater temperature can be raised in a short time). Furthermore, since the surface area of the heater 18 is made small to reduce the amount of heat radiated from the area, the electric current can be reduced by that amount.

[0122] (2) Since atomization of the fuel spray can be promoted and the most of the fuel spray can be carried by the air, an amount of fuel reaching the heater 18 ca be reduced and the heater current corresponding to the latent heat of vaporization can be reduced.

[0123] (3) Since the large amount of air flowing out from the carrier air passage 45 to the main passage 12 is prevented from directly hit against the heater, an amount of heat removed by the air can be reduced and the electric current can be reduced by that amount.

[0124] (4) Since the projected portion 20 is arranged upstream of the heater 18 so that the air flowing from upstream of the heater 18 may not directly hit against the heater 18, an amount of the heat removed by the air can be reduced and the electric current can be reduced by that amount.

[0125] (5) Since the thermal insulator 19 is arranged in order to reduce an amount of heat transferred from the heater 18 to the wall surface of the main passage 12, the electric current can be reduced by that amount.

[0126] Further, if the body 11 forming the main passage 12 is made of a resin not metal, the heater current can be further reduced because the heat transfer to the main passage 12 can be reduced.

[0127]FIG. 6(a) is a graph showing the relationship between droplet size if the fuel spray and limit of delaying (retarding) ignition timing while stability of combustion is being kept. Since the droplet size of the fuel spray obtained in the present embodiment is very small, the ignition timing can be largely retarded before the expansion stroke is started. Since the expansion ratio of the burned gas inside the combustion chamber is reduced if ignition is performed in the expansion stroke, an amount of heat consumed by the expansion work of the burned gas is reduced and accordingly the burned gas kept at a high temperature can be exhausted to the exhaust pipe. That is, as shown in FIG. 6(b), the ternary catalyst converter 24 can be rapidly warmed up by exhausting the high temperature burned gas by retarding the ignition timing, and the time after starting operation of the internal combustion engine 1 until the temperature of the ternary catalyst converter 24 reaches the activation temperature can be shortened.

[0128] That is, as shown in FIG. 6(c), since the cleaning effect of the ternary catalyst converter 24 is early started, an amount of exhausted HC after starting operation of the internal combustion engine 1 can be substantially reduced. In addition to HC, an amount of exhausted NOx and CO can be also reduced by shortening the warming-up period of the ternary catalyst converter (catalyst) 24.

[0129] Further, the assembly pipe fuel injector 15 is a fuel injector of which the fuel injection hole is exposed in the depth of the depressed portion 161 opening to the downstream portion of the throttle valve 4 of the main passage 12 of the body 11 in the intake air control device 110 mounted at a position upstream of the intake assembly pipe 6. Therefore, the fuel spray 17 injected from the assembly pipe fuel injector 15 is sufficiently promoted in atomization while passing through the inside of the depressed portion 161, and distribution of the fuel spray 17 to each of the cylinders can be made uniform since the distance for promoting mixing with the intake air and for atomizing before reaching each of the cylinders becomes longer.

[0130] The second embodiment in accordance with the present invention will be described below, referring to FIG. 8.

[0131] A main different point of the second embodiment from the first embodiment shown in FIG. 2 is the construction of the bypass flow passage 13 c through which the air for carrying the fuel spray flows, the other constructions are the same as those of the first embodiment. Therefore, the overlapped explanation will be omitted here.

[0132] In this embodiment, the bypass flow passage 13 c branched at a branch inlet portion 43 a is communicated with a branch outlet portion 60 a formed in the body 11 so as to project in the main passage 12 between the throttle valve 4 and the depressed portion 161. The branch outlet portion 60 a is opened toward the downstream side of the axial flow direction of the main passage 12. That is, the air 104 flowing out from the branch outlet portion 60 a collides (merges) with the fuel spray 17 promoted in atomization in the depressed portion 161 by being injected from the circular hole 46 at the portion of the fuel spray 17 flowing out to the main passage 12. At that time, the air 104 flowing out from the branch outlet portion 60 a is mostly composed of the air flowing through the ISC valve 14 of which the flow rate is large, and is the flow directing to the downstream side of the axial flow direction of the main passage 12.

[0133] Therefore, the fuel spray 17 is transported by being diverted toward the downstream direction of the main passage 12. The small size droplets among the fuel spray 17 can be transported toward the downstream direction of the heater by being carried along the flow of the air 104. On the other hand, very large size droplets among the fuel spray 17 attach to the heater 18 without affected by the flow of air 104. However, an amount of the fuel reaching the heater 18 is very small, and accordingly the heater 18 can be made small in size or can be eliminated.

[0134] The third embodiment in accordance with the present invention will be described below, referring to FIG. 9.

[0135] A main different point of the third embodiment from the first embodiment shown in FIG. 2 is that instead of the throttle valve 4 operated linking to accelerator operation of a driver, an electronic control throttle valve (hereinafter, referred to as ETC) 52 for electrically controlling the opening degree is provided, and accordingly the ISC valve 14 is eliminated. When the ETC valve 52 is used, the amount of intake air at starting operation of the internal combustion engine 1 and during idling operation can be controlled without using the ISC valve 14. Therefore, the ISC valve 14 is unnecessary. Further, the construction of the carrier air passage 45 a is changed as to be described later. The other constructions are the same as those of the first embodiment. Therefore, the overlapped explanation will be omitted here.

[0136] In this embodiment, the assembly pipe fuel injector 15, the circular hole 46 and the depressed portion 161 are arranged in the body 11 b so that the center shaft of the assembly pipe fuel injector 15 is included in a plane formed by the rotating shaft 53 of the ETC valve 52 and the axial direction of the main passage 12. Further, the heater 18 is placed in a portion where the fuel injected from the assembly pipe fuel injector 15 reaches, that is, is placed on the inner wall surface of the main passage 12 near a point where a line extending the center axis (the valve shaft center) of the assembly pipe fuel injector 15 intersects with the wall surface of the main passage 12. These intersecting points are included in the plane formed by the rotating shaft 53 of the ETC valve 52 and the axial direction of the main passage 12.

[0137] Therein, the ETC valve 52 is always opened at starting of operation and during operation of the internal combustion engine 1 though the opening degree is varied.

[0138] As shown in FIG. 9(b), the air 102 passing through the ETC valve 52 is large in an amount of flow passing through the central portion of the ETC opening portions 55 and very small in an amount of flow passing through the portion where there is the rotating shaft 53 of the ETC valve 52. Therefore, when the heater 18 is placed at the position downstream of the main passage 12 near the plane including the rotating shaft 53, an amount of air 102 hitting against the heater 18 becomes small to reduce the amount of heat removed from the heater 18 by the air 102, and accordingly the electric power consumed by the heater 18 can be reduced.

[0139] Further, in such a construction, since the distribution of air between the air 101 flowing through the bypass flow passage 13 and the air 102 flowing through the ETC opening portion 55 of the ETC valve 52 can be controlled by the opening degree of the ETC valve 52, it is possible to control the distribution ratio of the an amount of fuel injected from the assembly pipe fuel injector 15 and an amount of the air flowing out from the circular hole 46 where the assembly pipe fuel injector 15 is placed. For example, when the opening degree of the ETC valve 52 is slightly increased, the amount of air 101 flowing through the bypass flow passage 13 is decreased. Since the ratio of the amount of air 103 to be mixed with the fuel is varied as described above, the condition of atomization and the condition of vaporization of the fuel spray 17 can be changed. That is, the condition of atomization and the condition of vaporization can be controlled depending on the operating condition of the internal combustion engine 1.

[0140] As shown in FIG. 9(c), the opening portion of the carrier air passage 45 a in the present embodiment is arranged with an offset by a distance L from the central axis in the axial direction of the main passage 12. By doing so, the air 104 flowing out to the main passage 12 from the carrier air passage 45 a through the outlet portion 60 a is diverted along the curved inner wall surface of the main passage 12 to form a swirl flow 54. At that time, since the pressure in the center of the swirl 54 is decreased, the fuel spray 17 injected from the assembly pipe fuel injector 15 and passed through the atomizing air outlet 46 and the air 103 are drawn toward the low-pressure center of the swirl flow 54 to be transported.

[0141] In this construction, since the effect of drawing the fuel spray 17 to the central axis of the main passage 12 is stronger than that of the case where the carrier air passages 45 are arranged opposite to each other inside the main passage 12, it is easy to prevent the fuel spray 17 from adhering onto the wall surface of the main passage 12.

[0142] The construction to form the swirl flow by the carrier air 104 is not necessary to combine with the ETC valve 52, but can be applied to the case where the ISC valve is used as in the first embodiment.

[0143] The fourth embodiment in accordance with the present invention will be described below, referring to FIG. 10.

[0144] In the fourth embodiment, although the ETC valve 52 is placed in the main passage 12 similarly to the third embodiment, different points of the fourth embodiment from the third embodiment are that a curved surface portion 201 for constructing an air flow passage of the ETC valve 52 is formed in the main passage 12, and that a water jacket 301 for recirculating cooling water 300 is arranged around the heater 18 in the main passage 12, and that the thermal insulator 19 provided the back surface of the heater 18 is eliminated. The other constructions are the same as those of the first embodiment. Therefore, the overlapped explanation will be omitted here.

[0145] In this embodiment, the assembly pipe fuel injector 15, the circular hole 46 and the depressed portion 161 are arranged in the body 11 c so that the center shaft of the assembly pipe fuel injector 15 is included in a vertical plane of the center axis of the main passage 12 to the plane formed by the rotating shaft 53 of the ETC valve 52.

[0146] The function of the curved surface portion 201 will be described below. The ETC passage portion 55 a is formed so that the passage between the curved surface portion 201 of the main passage 12 (the inner wall surface of the maim passage 12) and the ETC valve 52 may be closed until the opening degree of the ETC valve 52 exceeds a given opening degree. The ECT passage portion 55 a is formed in the depressed portion 161 side (the side where the assembly pipe fuel injector 15 is provided) in the main passage 12.

[0147] The inner wall surface of the main passage 12 in the opposite side is formed so as to have a gap with the locus of an outer peripheral surface of the ETC valve 52 for performing opening and closing operation of the curved surface portion 201 which has a curvature nearly equal to the rotating locus of the outer shape of the ETC valve 52 opening and closing using a rotating shaft 53 as the axis. By doing so, the ECT valve 52 in the opposite side does not form any substantial air passage until the given opening degree.

[0148] At starting operation and during warming-up operation of the internal combustion engine 1, the amount of intake air is controlled mainly using the ECT passage portion 55 a. Further, since the ECT passage portion 55 a is formed in the depressing portion 161 side, the air 102 passing through the ECT passage portion 55 a collides with the fuel spray 17 at the portion where the fuel spray injected from the circular hole 46 and promoted in the atomization inside the depressed portion 161 flows out to the main passage 12, and diverts and transports the fuel spray 17 toward the downstream side of the main passage 12. Therefore, the amount of the fuel spray 17 reaching (adhering onto) the heater 18 becomes very small.

[0149] Operation of the water jacket 301 arranged around the heater 18 inside the body 11 c will be described below. In an operating region such as hard acceleration, high speed running or the like in operating conditions other than starting operation and during warming-up operation of the internal combustion engine 1, a large amount of fuel is required. At that time, the atomization-promoted fuel spray 17 is injected from the assembly pipe fuel injector 15 together with the injection of fuel from the port fuel injector 10. Temperature of the cooling water 300 recirculating in the water jacket 301 arranged around the heater 18 is heated up to several tens °C after warming-up of the internal combustion engine 1, and vaporization of fuel can be promoted by using the heat. Therefore, current supply to the heater 18 is not required so much, and accordingly the capacity of the heater 18 can be reduced.

[0150] The amount and the velocity of intake air flowing in the intake pipe including the main passage 12 at hard acceleration and high speed running are very large and very high compared to those at starting operation and during warming-up operation of the internal combustion engine 1. Therefore, the fuel spray 17 injected from the assembly pipe fuel injector 15 and promoted in atomization and the vaporized fuel vapor can be efficiently transported to the combustion chambers 25.

[0151] The embodiment that the water jacket 301 is arranged around the heater 18 to recirculate the cooling water 300 can be applied to all the embodiments of the present invention. Further, in the present embodiment, although the intake air 101 of the bypass flow passage 13 is divided into flows of intake air 103 and 104, it is possible to construct that all the intake air 101 is supplied to the pressure regulation chamber 41 to be used only for the atomization of the fuel spray 17 without forming the bypass flow passage 13 b the pressure regulation chamber 42 and the carrier air passage 45. By doing so, it is possible to provide an intake air control device 11 which is simple in structure and excellent in productivity while keeping atomization ability and carrying power of the fuel spray 17.

[0152] The fifth embodiment in accordance with the present invention will be described below, referring to FIG. 11.

[0153] A main different point of the fifth embodiment from the first embodiment shown in FIG. 2 is that the carrier air passage 45 formed in the body 11 is modified, and the projected portion 20 is eliminated. The other constructions are the same as those of the first embodiment. Therefore, the overlapped explanation will be omitted here.

[0154] In the present embodiment, the carrier air passage 45 b communicating the pressure regulation chamber 42 with the main passage 12 in the body 11 d is formed slanting in the downstream side by a given angle along the axial flow direction in the main passage 12, and the outlet portion 60 c is formed so as to open toward the heater 18 arranged in the main passage 12. Further, the shape of the outlet portion 60 c of the carrier air passage 45 b is formed so as to have a desired shape and a passage area, as shown in FIG. 11(b). Therein, the outlet portion 60 c is long-ellipsoidal, and a length of the major axis of the long-ellipse is nearly equal to a width of the heater 18 arranged in the main passage 12.

[0155] The heater 18 is placed inside the main passage in the downstream side of the throttle valve 4 and the downstream side of the assembly pipe fuel injector 15. Further, the projected portion 20, which is arranged in the upstream side of the heater 18 in the main passage 12 in the first embodiment, is eliminated in this embodiment.

[0156] The fuel spray 17 injected from the assembly pipe fuel injector 15 is promoted in the atomization in the depressed portion 161 by the intake air 103 passing together through the circular hole 46, and the fuel spray 17 is supplied into the main passage 12 toward the heater 18.

[0157] On the other hand, the intake air 104 supplied to the main passage 12 from the pressure regulation chamber 42 through the carrier air passage 45 b is flows toward the heater 18 with a preset angle and a velocity.

[0158] Therein, most of the atomized fuel spray 17 is not attached onto the heater 18, and is transported to the combustion chambers 25 without adhering onto the inner wall surface of the main passage 12 and the inner wall surface of the intake pipe. On the other hand, by actively supplying the intake air 104 to the heater 18 with a preset velocity, very large droplets attached onto the surface of the heater 18 are efficiently vaporized by being expanded on the heater 18 and by increasing the heat transfer. The reason why the heat transfer is increased and the fuel is efficiently vaporized is that the fuel vapor vaporized by the heater 18 is efficiently swept and transported by the intake air 104.

[0159] Further, since the projected portion is not formed in the upstream side of the heater 18 in the main passage 12, the intake air flowing from the upstream side is also supplied on the surface of the heater 18, and the fuel vapor vaporized by the heater 18 is actively swept and transported. That is, although the intake air 104 is actively supplied to the heater 18, the intake air 104 mainly expands the very large droplets attached onto the heater 18 along the surface of the heater 18 to vaporize the very large droplets, and works to sweep and transport the vaporized fuel vapor. Therefore, increase of the consumed electric power due to heat removing from the heater 18 by the intake air 104 can be suppressed to a relatively small amount.

[0160] Therefore, in the present embodiment, the electric power consumed by the heater 18 is slightly increased compared to that in the first to the fourth embodiments, but the other effects similar to those of the above-mentioned embodiments can be also obtained. Further, although the ISC valve 14 is used in the present embodiment, it is possible to use the ETC valve 52 electrically controlling the valve opening degree to control the amount of intake air at starting operation and during warming-up operation of the internal combustion engine 1.

[0161] The sixth embodiment in accordance with the present invention will be described below, referring to FIG. 12.

[0162] In the sixth embodiment, the ETC valve 52 is placed in the main passage 12 of the body 11 e, similarly to the fourth embodiment shown by FIG. 10, different points of the sixth embodiment from the fourth embodiment are that a curved surface portion 201 is arranged in the depressed portion 161 side in the main passage 12 and the ETC passage portion 55 b is formed in the heater 18 side, and that the pressure regulation chamber 42 downstream of the heater 18, the carrier air passage 45 and the water jacket 301 are eliminated, and that the projected potion 20 is eliminated. The other constructions are the same as those of the fourth embodiment. Therefore, the overlapped explanation will be omitted here.

[0163] The fuel spray 17 injected from the assembly pipe fuel injector 15 is promoted in the atomization in the depressed portion 161 by the intake air 103 passing together through the circular hole 46, and the fuel spray 17 is supplied into the main passage 12 toward the heater 18. The intake air 102 passing through the ETC passage portion 55 b formed in the upstream side of the heater 18 in the main passage 12 passes on the heater 18 with a desired flow speed. At that time, the atomization-promoted fuel spray 17 is transported downstream of the heater by the intake air 102 to be efficiently supplied to the combustion chamber 25. On the other hand, very large droplets not transported by the intake air 102 pass through the intake air 102 to attach onto the heater 18. Therefore, the amount of the fuel spray 17 attached onto the heater 18 is reduced.

[0164] The very large droplets not transported by the intake air 102 are attached onto the heater 18 and vaporized. Therein, by actively supplying the intake air 104 to the heater 18 with a preset velocity, very large droplets attached onto the surface of the heater 18 are efficiently vaporized by being expanded on the heater 18 and by increasing the heat transfer. The reason why the heat transfer is increased and the fuel is efficiently vaporized is that the fuel vapor vaporized by the heater 18 is efficiently swept and transported by the intake air 104.

[0165] In the present embodiment, since only the very large droplets of part of the fuel spray 17 attach onto the heater 18, the electric power consumed by the heater 18 can be suppressed relatively small. Therefore, compared to the other embodiments not directly supplying the intake air to the heater 18, the electric power consumed by the heater 18 is increased a little, but the other effects can be similarly obtained.

[0166] The seventh embodiment in accordance with the present invention will be described below, referring to FIG. 13.

[0167] Main different points of the seventh embodiment from the second embodiment shown by FIG. 8 are the structure of the bypass flow passage 13 d for flowing the air 104 to carry the fuel spray 17, and the structures of the heater 18 for vaporizing the fuel spray 17 and the thermal insulator 19, and that the projected portion 20 is eliminated. The other constructions are the same as those of the second embodiment. Therefore, the overlapped explanation will be omitted here.

[0168] In this embodiment, the bypass flow passage 13 d branched at the branch inlet portion 43 b in the body 11 f is communicated with the branch outlet portion 60 d formed in the main passage 12 between the throttle valve 4 and the depressed portion 161. The branch outlet portion 60 dis opened toward the heater 18 to be described later. That is, the air 104 flowing out from the branch outlet portion 60 d is jetted toward the heater 18. Since the heater 18 is formed together with the thermal insulator 19 in a one-piece structure and covered by the thermal insulator 19 in the back surface, the heat generated by the heater 18 is difficult to be radiated from the thermal insulator 19 side, and most part of the generated heat is dissipated from the surface of the heater 18 which is not covered with the thermal insulator 19. The heater 18 is arranged along the axial flow in the main passage 12 downstream of the throttle valve 4 so as to divide the main passage into a passage 12 a in the depressed portion 161 side and the passage 12 b in the opposite side opposite to the passage 12 a.

[0169] The intake air 104, the fuel spray 17 and the intake air 103 are supplied toward the heater 18 provided so as to face the passage 12 a. Therefore, the velocity of the intake air 104, the fuel spray 17 and the intake air 103 becomes faster because the passage 12 a is contracted compared to the passage area inside the main passage 12 in the downstream side. The fuel spray 17 directed toward the heater 18 in the passage 12 a is effectively transported toward the downstream side of the main passage 12 by the intake air 104 which is most part of intake air passing through the ISC valve 14.

[0170] Only the very large droplets not transported by the intake air 104 are attached onto the heater 18. By actively supplying the intake air 104 with a preset velocity, the very large droplets attached onto the surface of the heater 18 are efficiently vaporized by increasing the heat transfer. The reason why the heat transfer is increased and the fuel is efficiently vaporized is that the fuel vapor vaporized by the heater 18 is efficiently swept and transported by the intake air 104. That is, the intake air 104 is actively supplied to the heater 18. However, since the very large droplets are attached onto the surface of the heater 18, the heat of the heater 18 is consumed in vaporization of the very large droplets (fuel) attached onto the surface of the heater 18 to decrease the ratio of heat consumed by being removed the intake air 104. Therefore, the consumed electric power can be suppressed relatively small.

[0171] Therefore, in the present embodiment, the electric power consumed by the heater 18 is slightly increased compared to that in the first to the fourth embodiments, but the other effects similar to those of the above-mentioned embodiments can be also obtained. Further, although the ISC valve 14 is used in the present embodiment, it is possible to use the ETC valve 52 electrically controlling the valve opening degree to control the amount of intake air at starting operation and during warming-up operation of the internal combustion engine 1.

[0172] Further, in the present embodiment, the heater 18 is preferably arranged close to the throttle valve 4 side, and the fuel spray 17 can be more efficiently transported by supplying part of the intake air 102 leaking through a gap between the main passage 12 and the throttle valve 4 to the heater 18.

[0173] The eighth embodiment in accordance with the present invention will be described below, referring to FIG. 14.

[0174] Main different points of the eighth embodiment from the second embodiment shown by FIG. 8 are the structure of the heater 18 a for vaporizing the fuel spray 17, and that the projected portion 20 is eliminated. The other constructions are the same as those of the second embodiment. Therefore, the overlapped explanation will be omitted here.

[0175] In this embodiment, the heater 18 a is composed of plate-shaped heaters, and a plurality of the plate-shaped heaters stacked with a spacing are arranged in the main passage 12 in the downstream side of the depressed portion 161. Therefore, the heater 18 a formed by stacking the plurality of plate-shaped heaters with a spacing and the flow of the intake air 104 passing through the inside of the passage 12 are parallel to each other. The injection direction of the fuel spray 17 atomized at the depressed portion 161 is slanted by an angle α to the surface of the plate-stack-shaped heater 18 a.

[0176] Therein, the present embodiment can hold when the shape of the heater 18 a is lattice-shaped, honeycomb and the like, in addition to plate-stack-shaped.

[0177] The intake air 104 flowing out from the branch outlet portion 60 a of the body 11 g into the main passage 12 collides (merges) with the fuel spray 17 at a portion where the fuel spray 17 atomized at the depressed portion 161 comes out to the main passage 12. At that time, the air 104 is mostly composed of the air flowing through the ISC valve 14 of which the flow rate is large, and is the flow directing to the downstream side of the axial flow direction of the main passage 12. Therefore, the fuel spray 17 is transported by being diverted toward the downstream direction of the main passage 12.

[0178] The small size droplets among the fuel spray 17 can be transported toward the downstream direction of the heater 18 a through the gaps between the plate-shaped heaters 18 a stacked with a spacing by being carried along the flow of the air 104. The very large size droplets among the fuel spray 17 are not so mush affected by the flow of air 104, and attach to the heater 18 a with the angle α between the heater 18 a and the injection direction of the fuel spray 17.

[0179] Therein, since the fuel spray 17 is promoted in the atomization by the intake air 103 in the depressed portion 161, most of the fuel spray 17 passes through the heater along the flow of the intake air 104 without colliding with the heater 18 a. Therefore, an amount of the fuel reaching the heater 18 is very small, and accordingly the consumed electric power required for vaporizing the fuel by the heater 18 a can be reduced.

[0180] Further, since velocity of the intake air 104 passing through the heater 18 a is relatively fast, vaporization of the fuel spray attached onto the heater 18 a can be effectively promoted. This is because the fuel spray 17 attached onto the surface of the heater 18 a is formed into liquid films by on the surface of the heater 18 a, and then the liquid films are expanded on the surface of the heater 18 a by the intake air flow, and the heat transfer is increased, and the fuel is efficiently vaporized, and the fuel vapor vaporized by the heater 18 a is efficiently swept and transported by the intake air 104.

[0181] The ninth embodiment in accordance with the present invention will be described below, referring to FIG. 15.

[0182] Main different points of the ninth embodiment from the fourth embodiment shown by FIG. 10 are the structure of the heater 18 b for vaporizing the fuel spray 17, and that the depressed portion 161 is placed near the ETC passage portion 55 a in the main passage 12, and that the projected portion 20, the water jacket 301, the cooling water 300, the bypass flow passage 13 b, the pressure regulation chamber 42 and the carrier air passage 45 are eliminated. The other constructions are the same as those of the fourth embodiment. Therefore, the overlapped explanation will be omitted here.

[0183] In this embodiment, the heater 18 b is arranged in the depressed portion 161 formed in the body 11 h, and the injection direction of the fuel spray 17 atomized at the depressed portion 161 is slanted by an angle α to the surface of the heater 18 b.

[0184] The heater 18 b is a plate-stack-shaped heater formed by stacking a plurality of the plate-shaped heaters with a spacing, similarly to that in the eighth embodiment. Therein, the present embodiment can hold when the shape of the heater 18 a is lattice-shaped, honeycomb and the like, in addition to plate-stack-shaped.

[0185] Since the depressed portion 161 is formed at a position near the downstream side of the ETC passage portion 55 a, the air 102 flowing through the ETC passage portion 55 a is concentrically supplied to the heater placed in the depressed portion 161. Therefore, the fuel spray 17 promoted in atomization in the depressed portion 161 by injected from the circular hole 46 collides (merges) with the intake air 102 passed through the ETC passage portion 55 a when passing through the depressed portion 161.

[0186] At that time, since the amount of the intake air 102 is large compared to that of the intake air 103, and the intake air 102 is concentrically supplied toward the heater 18 b. Therefore, the small size droplets among the fuel spray 17 can be transported toward the downstream direction of the heater 18 b through the gaps between the plate-shaped heaters 18 b stacked with a spacing by being carried along the flow of the air 102.

[0187] The very large size droplets among the fuel spray 17 are not so mush affected by the flow of air 102, and attach to the heater 18 a with the angle α between the heater 18 a and the injection direction of the fuel spray 17. Therefore, since only the very large droplets are attached onto the heater 18 b, an amount of fuel attached onto the heater 18 b is very small. Thus, the electric power required for vaporization of the fuel and consumed by the heater 18 b can be reduced.

[0188] Further, since velocity of the intake air 102 passing through the heater 18 b is relatively fast, vaporization of the fuel spray attached onto the heater 18 b can be effectively promoted. This is because the fuel spray 17 attached onto the surface of the heater 18 b is formed into liquid films by on the surface of the heater 18 b, and then the liquid films are expanded on the surface of the heater 18 b by the intake air flow, and the heat transfer is increased, and the fuel is efficiently vaporized. This is caused by that the fuel vapor vaporized by the heater 18 b is efficiently swept and transported by the intake air 102.

[0189] The tenth embodiment in accordance with the present invention will be described below, referring to FIG. 16.

[0190] A main different point of the tenth embodiment from the second embodiment shown by FIG. 8 is the body 11 i in which the bypass flow passage 13 a branched from the bypass flow passage 13 and the passage forming projected portion 49 are eliminated. Therefore, the pressure regulation chamber 41 formed by inserting the assembly pipe fuel injector 15 into the injector insertion portion 16 is eliminated. Since the passage forming projected portion 49 is eliminated, the shoulder portion 51 of the assembly pipe fuel injector 15 is in contact with the bottom portion of the injector insertion portion 16, and the nozzle 47 is inserted into the circular hole 46 so that the front end surface of the nozzle 47 faces inside the depressed portion 161. Further, the projected portion 20 formed in the main passage 12 is eliminated. The other constructions are the same as those of the second embodiment. Therefore, the overlapped explanation will be omitted here.

[0191] In this embodiment, since the intake air 103 passed through the bypass flow passage 13 a for atomizing the fuel spray 17 does not exist, promoting of atomization of the fuel spray is not performed. The droplet size of the fuel spray 17 is determined by the condition of injection from the assembly pipe fuel injector 15.

[0192] The intake air 101 flowing out from the branch outlet portion 60 a collides (merges) with the fuel spray 17 at a portion where the fuel spray 17 injected from the assembly pipe fuel injector 15 flows out into the main passage 12 through the depressed portion 161. Therein, since the intake air 101 is the total amount of air passing through the ISC valve 14 and is the flow flowing toward the downstream side of the axial flow direction of the main passage 12, the fuel spray 17 is easily diverted and transported toward the downstream side of the main passage 12.

[0193] Thereby, the small size droplets among the fuel spray 17 can be transported toward the downstream direction of the heater 18 by being carried along the flow of the air 101. The very large size droplets among the fuel spray 17 are not affected by the flow of air 101, and attach to the heater 18 to be vaporized. Therefore, an amount of fuel attached onto the heater 18 is very small. Thus, the electric power required for vaporization of the fuel and consumed by the heater 18 b can be reduced.

[0194] However, the fuel spray 17 injected from the assembly pipe fuel injector 15 is not promoted in the atomization of the fuel spray 17 compared to that in the case where the atomization is promoted using the atomizing air, and accordingly the amount of fuel adhering onto the heater 18 is increased. Therefore, the electric energy consumed by the heater 18 is increased. However, since a very large amount of the intake air 101 is collided (merged) with the fuel spray 17, the small sized liquid droplets in the fuel spray 17 do not attach onto the heater 18, and accordingly the electric energy consumed by the heater 18 can be decreased by that amount.

[0195] Further, if the branch outlet portion 60 a is placed in the upstream of the heater 18 and in the side placing the heater 18 in the main passage 12, the intake air passing above the surface of the heater 18 can be concentrated and accordingly the velocity of the intake air passing by the surface of the heater 18 can be made faster. By constructing as described above, the fuel spray 17 attached onto the surface of the heater 18 is formed into liquid films by on the surface of the heater 18, and then the liquid films are expanded on the surface of the heater 18 by the intake air flow, and the heat transfer is increased, and the fuel is efficiently vaporized. This is caused by that the fuel vapor vaporized by the heater 18 is efficiently swept and transported by the intake air 102.

[0196] However, the fuel spray 17 injected from the assembly pipe fuel injector 15 is not promoted in the atomization of the fuel spray 17 compared to that in the case where the atomization is promoted using the atomizing air, and accordingly the amount of fuel adhering onto the heater 18 is increased. Therefore, the electric energy consumed by the heater 18 is increased.

[0197] The eleventh embodiment in accordance with the present invention will be described below, referring to FIG. 17.

[0198] A main different point of the eleventh embodiment from the sixth embodiment shown by FIG. 12 is the body 11 j in which the bypass flow passage 13 and the passage forming projected portion 49 are eliminated. Therefore, the pressure regulation chamber 41 formed by inserting the assembly pipe fuel injector 15 into the injector insertion portion 16 is eliminated. Since the passage forming projected portion 49 is eliminated, the shoulder portion 51 of the assembly pipe fuel injector 15 is in contact with the bottom portion of the injector insertion portion 16, and the nozzle 47 is inserted into the circular hole 46 so that the front end surface of the nozzle 47 faces inside the depressed portion 161. The other constructions are the same as those of the sixth embodiment. Therefore, the overlapped explanation will be omitted here.

[0199] In this embodiment, since the intake air 101 passed through the bypass flow passage 13 for atomizing the fuel spray 17 does not exist, promoting of atomization of the fuel spray by the intake air 101 is not performed. The droplet size of the fuel spray 17 is determined by the condition of injection from the assembly pipe fuel injector 15. The intake air 101 flowing out from the ETC passage portion 55 b collides (merges) with the fuel spray 17 above the heater 18 inside the main passage 12. Therein, since the intake air 102 is the total amount of air passing through the ETC valve 15 and is the flow flowing toward the downstream side of the axial flow direction of the main passage 12. Therefore, the fuel spray 17 is easily diverted and transported toward the downstream side of the main passage 12.

[0200] Thereby, the small size droplets among the fuel spray 17 can be transported toward the downstream direction of the heater 18 by being carried along the flow of the air 102. The very large size droplets among the fuel spray 17 are not affected by the flow of air 102, and attach to the heater 18 to be vaporized. Therefore, an amount of fuel attached onto the heater 18 is very small. Thus, the electric power required for vaporization of the fuel and consumed by the heater 18 can be reduced.

[0201] Further, since the intake air 102 passing above the surface of the heater 18 is concentrated to pass through the ETC passage portion 55 b, and accordingly the velocity is relatively faster. Therefore, the fuel spray 17 attached onto the surface of the heater 18 is formed into liquid films by on the surface of the heater 18, and then the liquid films are expanded on the surface of the heater 18 by the intake air flow, and the heat transfer is increased, and the fuel is efficiently vaporized. This is caused by that the fuel vapor vaporized by the heater 18 is efficiently swept and transported by the intake air 102.

[0202] However, the fuel spray 17 injected from the assembly pipe fuel injector 15 is not promoted in the atomization of the fuel spray 17 compared to that in the case where the atomization is promoted using the atomizing air, and accordingly the amount of fuel adhering onto the heater 18 is increased. Therefore, the electric energy consumed by the heater 18 is increased.

[0203] The twelfth embodiment in accordance with the present invention will be described below, referring to FIG. 18.

[0204] Main different points of the twelfth embodiment from the third embodiment shown by FIG. 9 are a drive motor 210 of the ETC valve 52 and a throttle positioning sensor (hereinafter, referred to as TPS) 211 are mounted onto the body 11 k of the intake air control device 110, and the shape of the connector 15 b of the assembly pipe fuel injector 15 a is changed, and that the wires (bold solid lines in the figure) connecting the assembly connector 212 to the drive motor 210, the TPS 211, the assembly pipe fuel injector 15 a and the heater 18 are embedded in the body 11 k. The other constructions are the same as those of the third embodiment. Therefore, the overlapped explanation will be omitted here.

[0205] In this embodiment, the shape of the connector 15 b of the assembly pipe fuel injector 15 a is changed, and connection of the wire connecting between the connector portion 15 b and the assembly connector 212 is performed by inserting the assembly pipe fuel injector 15 a into the injector insertion portion 16 provided in the body 11 k. Further, the heater 18, the drive motor 210 and the TPS 211 are individually connected to the assembly connector 212 through the wires. Therefore, the components mounted in the body 11 k and controlled by the controller 32 (not shown) can be controlled through the single assembly connector 212 provided in the body 11 k. Therein, the assembly connector is integrated with the body 11 k in one-piece structure.

[0206] Further, at least the wiring portion periphery of or the whole of the body 11 k is made of an electrically non-conductive material. For example, it is preferable to use PBT resin which is electrically non-conductive, and excellent in stiffness, heat resistance, abrasion resistance and so on. Further, by forming the sliding portion between the ETC valve 52 and the main passage 12 using members less in thermal deformation made of aluminum or the like, the reliability can be improved.

[0207] Further, the assembly connector 212 is connected so as to control each of the components arranged in the body 11 k by control signals from the controller 32 (not shown) corresponding to an operating condition of the internal combustion engine 1.

[0208] By the construction described above, connectors of the components arranged in the body 11 k can be integrated into the assembly connector 212, and the wires can be embedded in the body 11 k. Therefore, the reliability of the wiring can be improved, and the ability of assembling the intake air control device 110 and the ability of mounting the intake air control device 110 to the internal combustion engine can be improved. Furthermore, since the wires are embedded in the electrically non-conductive material, leakage of current from the wires does not occur to improve the safety.

[0209] The feature of the present embodiment can be applied to the above-described embodiments, for example, can be applied to the intake air control device in which the ISC valve 14 is integrated in the body 11 in a one-piece structure.

[0210] Although the assembly pipe fuel injector 15 used in each of the embodiments described above employs a single-hole nozzle fuel injector having a single-hole nozzle, it is preferable to employ a multi-hole nozzle fuel injector having a multi-hole nozzle in order to perform controlling of fuel spray 17 shape and promoting of the atomization. a step-shaped nozzle fuel injector which has a step in the front end nozzle of the fuel injection hole in the outlet side or a slit nozzle fuel injector is preferable in order to perform controlling of fuel spray 17 shape.

[0211] Description will be made below on differences in the shape of fuel spray and the shape of fuel spray adhering onto a heater depending on differences in various kind of shapes of spray nozzle, referring to FIG. 19.

[0212] In the case of a single-hole nozzle 47, the shape of the fuel spray 17 injected from the fuel injection hole 70 becomes a conical spray shape. Therefore, the front end shape of the injection hole is symmetric with respect to the axis of the nozzle, and the spray shapes seeing from direction of the arrow A and the direction of arrow B become equal to each other, and the outermost angles θ1 and θ2 of the fuel spray 17 become equal to each other. The shape of the fuel spray 17 adhering onto the surface of the heater 18 becomes nearly circular. However, the shape of the fuel spray 17 adhering onto the surface of the heater 18 becomes ellipsoidal due to the attaching angle α between the assembly pipe fuel injector 15 and the central axis of the main passage 12, as shown by the filled-in area in the figure.

[0213] In the case of the multi-hole nozzle 47 a, a multi-hole plate 80 having a plurality of small holes 81 is placed downstream of the fuel injection hole 70. Each of the injection holes 81 is very smaller compared to the fuel injection hole 70. Therefore, the droplet size of the fuel spray 17 injected from the injection holes 81 becomes smaller compared to the droplet size of the fuel spray 17 injected from the single-hole fuel injection hole 70. Therefore, the penetration force of the fuel spray 17 becomes smaller, and the traveling distance of the spray (hereinafter, referred to as penetration) becomes shorter. Further, since the directivity of the spray injected from each of the injection hole 81 can be controlled by adding a directivity to the injection holes 81 bored in the multi-hole plate 80, the angle of the fuel spray 17 can be relatively easily set to a desired value.

[0214] Therefore, since the spray angles θ1 and θ2 can be easily set, the shape of fuel spray 17 adhering onto the surface of the heater 18 can be arbitrarily set. For example, the filled-in area of the heater 18 portion illustrated in the lowermost row in the column of multi-hole nozzle of FIG. 19 can be changed to set to the area surrounded by the dotted line. Thereby, the droplet size of the fuel spray 17 can be made smaller, and the penetration can be also shortened, and the area of the fuel spray 17 attaching on the heater 18 can be widened. Therefore, heat from the heater 18 can be efficiently transferred to the fuel attached onto the heater 18, and accordingly the vaporization of the fuel can be promoted.

[0215] In the case of the step nozzle 47 b, an uneven-distribution spray can be formed by cutting away the front end of the nozzle 47 b including a part of the fuel injection hole 70 in a given depth as the cutting-away portion 71 illustrated by the hatched area. In this case, the droplet size of the fuel spray 17 becomes larger than that of the fuel spray injected from the single-hole nozzle by several μm. However, the uneven distribution of the fuel spray can be made by forming the cutting-away portion 71, and the penetration of the fuel spray 17 can be shortened. Further, since the shape of the fuel spray 17 adhering onto the surface of the heater 18 can be widened, and the vaporization of the fuel can be promoted because heat from the heater 18 can be efficiently transferred to the attached fuel.

[0216] In the case of the slit nozzle 47 c, the shape of the fuel spray 17 can be made flat by forming a slit groove 72 on the front end of the nozzle 47 c with a given width and a given depth so as to pass across on the fuel injection hole 70 as the slit groove 72 illustrated by the hatched area. Similarly to the step nozzle 47 b, the droplet size of the fuel spray 17 becomes larger than that of the fuel spray injected from the single-hole nozzle by several μm. However, by flattening the flat distribution of the fuel spray 17 by forming the slit groove 72, the penetration of the fuel spray 17 can be shortened. Further, since the shape of the fuel spray 17 adhering onto the surface of the heater 18 can be widened, and accordingly the vaporization of the fuel can be promoted because heat from the heater 18 can be efficiently transferred to the attached fuel.

[0217] By the various kinds of nozzle shapes described above, the penetration of the fuel spray 17 can be suppressed, and the shape of the fuel spray attached onto the surface of the heater can be set to a desired shape because the shape of the spray can be easily set to a desired shape, and vaporization of the spray can be efficiently promoted by improving heat transfer from the heater 18 to the fuel attached on the heater 18. Further, by selectively employing one among various kinds of assembly pipe fuel injector having the various kinds of nozzles as described above, an intake air control device having characteristics preferable for various kinds of engines can be constructed.

[0218] In all the embodiments in accordance with the present invention described above, in the relationship between the average droplet size of the fuel spray 17 injected from the assembly pipe fuel injector 15 and the average droplet size of the fuel spray injected from the port fuel injector 10, there is always the relationship that the average droplet size of the fuel spray 17 injected from the assembly pipe fuel injector 15 is always smaller than the latter.

[0219] Further, all the embodiments in accordance with the present invention described above have been described by taking what is called the internal combustion engine 1 of a port injection type having the port fuel injectors 10 for injecting fuel to individual cylinders in the intake manifold 7 as the example. However, the same effects can be obtained by applying the present invention to what is called the internal combustion engine 1 of an in-cylinder injection type in which fuel is directly injected into the combustion chambers of the internal combustion engine 1.

[0220] Each of the embodiments described above may be considered to be a fuel injector having a throttle valve and a drive mechanism for driving the throttle valve, and may be also considered to be a throttle device (an intake air control device) having a fuel injector. In any case, since the fuel injector and the throttle device are constructed in the single body 11 in a form of one-piece structure which can be mounted on and dismounted from the intake air pipe, the assembling, the adjustment and the maintenance can be easily performed. Particularly, in the case of the electronic control throttle valve, operation of the throttle valve and operation of the fuel injector at starting operation of the internal combustion engine can be easily checked.

[0221] In each of the embodiments described above, the fuel spray 17 is transported from the assembly pipe fuel injector 15 until flowing into the main passage by the air flow merging at the outlet of the fuel injection hole so as to reduce being attached onto the wall of the passage, and after flowing into the main passage, transported by the carrier air after flowing into the main passage so as to reduce being attached onto the wall of the main passage. That is, the fuel spray and the carrier air merge with each other after flowing into the main passage. The carrier air merge (collide) with the fuel spray in the main passage with a desired directivity, for example, a directivity along the main passage, or a directivity guiding to the fuel vaporizer.

[0222] As having been described above, according to the present invention, since the fuel spray for warming-up operation can be efficiently transported to the cylinders by one or two air flows so as to reduce an amount of fuel adhering onto the wall of the passage by atomizing, it is possible to provide the intake air control device capable of reducing an amount of HC exhausted at warming-up operation of the engine. Further, since the fuel spray is made to appropriately contact with the heater by the carrier air, consumption of electric power required to vaporize the fuel can be reduced.

[0223] Further, since the intake air control device described above is formed in a unit which is mainly composed of the air passage integrated in a body forming the main passage to place the throttle valve therein and the fuel injector fit to the body, the intake air control device is easily manufactured and easily attached to and detached from the internal combustion engine. 

What is claimed is:
 1. An intake air control device comprising a body having a main flow passage for supplying air to cylinders of an internal combustion engine and a throttle valve for controlling an air flow rate arranged inside said main flow passage; and a fuel injector for supplying fuel into said main flow passage, said fuel injector being fit and attached to said body, wherein said body is formed by working a body member into a one-piece structure comprising an opening portion communicating an outer portion of said body with said main flow passage is a downstream side of said throttle valve; a mounting portion for fitting and attaching said fuel injector facing an opening plane of said opening portion; a first bypass flow passage communicating with said inside of said main flow passage through said opening portion, said first bypass flow passage being branched from said main flow passage in an upstream side of said throttle valve; and a second bypass flow passage communicating with said inside of said main flow passage in the downstream side of said throttle valve and in said upstream side or said downstream side of said opening portion, said second bypass flow passage being branched from said main flow passage in said upstream side of said throttle valve.
 2. An intake air control device according to claim 1 , wherein said body is constructed so as to be detachable together with said throttle valve from an intake pipe for supplying air to said internal combustion engine.
 3. An intake air control device according to claim 1 , wherein said body is arranged inside said main flow passage in the downstream side of fuel spray injected from said fuel injector, and contains a fuel atomizer for vaporizing fuel by heating.
 4. An intake air control device according to claim 1 , wherein a plurality of outlets of said second bypass flow passage are formed on an inner peripheral surface of said main flow passage along a peripheral direction.
 5. An intake air control device according to claim 1 , wherein a heater is arranged on a wall surface of said main flow passage at a position in a direction of fuel injection of said fuel injector, and a rotating shaft of said throttle valve and a central axis of said direction of said fuel injection of said fuel injector are arranged neatly flush with each other.
 6. An intake air control device according to claim 5 , wherein said throttle valve is a throttle valve of which an valve opening degree is electrically controlled.
 7. An intake air control device according to claim 3 , wherein a passage of a cooling water recirculating the internal combustion engine is arranged around said fuel atomizer.
 8. An intake air control device according to claim 1 , wherein said fuel injector injects fuel splitting into plural times by opening a valve the several times with a short cycle during one cycle of a fuel injection determined by a duty ratio.
 9. An internal combustion engine comprising first fuel injectors each injecting fuel to each of cylinders; and an intake air control device connected to an intake air passage in the upstream side of said first fuel injector, wherein said intake air control device is according to any one of claims 1 to 8 . 